Apparatus, system and method for therapeutic treatment of obstructive sleep apnea

ABSTRACT

Provided is an implantable RFID-enabled micro-electronic neurostimulator system for treating obstructive sleep apnea, comprising an implant having a top and a bottom layer, the bottom layer serving as an attachment mechanism such that the bottom layer of the implant encompasses the hypoglossal nerve and attaches to the top layer of the implant; a printed circuit board (PCB) attached to the top layer of the implant, the PCB having a first and a second opposing sides; a neural interface attached to the second side of the PCB; a core subsystem (CSS) attached to the first side of the PCB and electrically connected to the neural interface; and a radio frequency (RF) interface attached to the first side of the PCB and electrically connected to the CSS, wherein the implant is powered and controlled by an external programmable controller.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Applications60/774,039, 60/774,040, and 60/774,041 filed on Feb. 16, 2006, which areexpressly incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to an apparatus, system, and method forimplantable therapeutic treatment of obstructive sleep apnea.

BACKGROUND OF THE INVENTION

Sleep apnea is a physiological condition affecting millions of peopleworldwide. It is described as an iterated failure to respire properlyduring sleep. Those affected by sleep apnea stop breathing during sleepnumerous times during the night. There are two types of sleep apnea,generally described in medical literature as central sleep apnea andobstructive sleep apnea. Central sleep apnea is a failure of the nervoussystem to produce proper signals for excitation of the muscles involvedwith respiration. Obstructive sleep apnea (OSA) is cause by physicalobstruction of the upper airway channel (UAW).

Obstruction of the upper airway is associated with a depression of therespiratory system caused by a loss of tone of the oropharyngeal musclesinvolved in maintaining UAW patency. As those muscles lose tone, thetongue and soft tissue of the upper airway collapse, blocking the upperairway channel. Blockage of the upper airway prevents air from flowinginto the lungs. This creates a decrease in blood oxygen level, which inturn increases blood pressure and heart dilation. This causes areflexive forced opening of the UAW until the patient regains normalpatency, followed by normal respiration until the next apneic event.These reflexes briefly arouse the patient from sleep (microarousals).

Current treatment options range from non-invasive approaches such ascontinuous positive applied pressure (CPAP) to more invasive surgicalprocedures such as uvulopalatopharyngoplasty (UPPP) and tracheostomy. Inboth cases patient acceptance and therapy compliance is well belowdesired levels, rendering the current solutions ineffective as a longterm solution-for therapeutic treatment of OSA.

Implants are a promising alternative to these forms of treatment.Pharyngeal dilation via hypoglossal nerve (XII) stimulation has beenshown to be an effective treatment method for OSA. The nerves arestimulated using an implanted electrode. In particular, the medial XIInerve branch (i.e., in. genioglossus), has demonstrated significantreductions in UAW airflow resistance (i.e., increased pharyngealcaliber).

Reduced UAW airflow resistance, however, does not address the issue ofUAW compliance (i.e., decreased UAW stiffness), another critical factorinvolved with maintaining patency. To this end, co-activation of boththe lateral XII nerve branches (which innervate the hyoglossus (HG) andstyloglossus (SG) muscles) and the medial nerve branch has shown thatthe added effects of the HG (tongue retraction and depression) and theSG (retraction and elevation of lateral aspect of tongue) result in anincreased maximum rate of airflow and mechanical stability of the UAW.

While coarse (non-selective) stimulation has shown improvement to theAHI (Apnea+Hypopnea Index) the therapeutic effects of coarse stimulationare inconclusive. Selective stimulation of the functional branches ismore effective, since each branch-controlled muscle affects differentfunctions and locations of the upper airway. For example, activation ofthe GH muscle moves the hyoid bone in the anterosuperior direction(towards the tip of the chin). This causes dilation of the pharynx, butat a point along the upper airway that is more caudal (below) to thebase of the tongue. In contrast, activation of the HG dilates theoropharynx (the most commonly identified point of collapse, where thetongue and soft palate meet) by causing tongue protrusion. Finally, thetongue retractor muscles (HG and SG) do not themselves generatetherapeutic effects, but they have been shown to improve upper airwaystability when co-activated with the HG muscle.

While electrical stimulation of the hypoglossal nerve (HGN) has beenexperimentally shown to remove obstructions in the UAW, currentimplementation methods require accurate detection of an obstruction,selective stimulation of the correct tongue muscles, and a coupling ofthe detection and stimulation components. Additionally, attempts atselective stimulation have to date required multiple implants withmultiple power sources, and the scope of therapeutic efficacy has beenlimited. A need therefore exists for an apparatus and method forprogrammable and/or selective neural stimulation of multiple implants orcontact excitation combinations using a single controller power source.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus, system; and method forselective and programmable implants for the therapeutic treatment ofobstructive sleep apnea.

In one embodiment, an implantable RFID-enabled micro-electronicneurostimulator system for treating obstructive sleep apnea includes anexternal subsystem and an internal subsystem. In this embodiment, theinternal subsystem includes an implant having a top and a bottom layer,the bottom layer serving as an attachment mechanism such that the bottomlayer of the implant encompasses the HGN and attaches to the top layerof the implant. A printed circuit board (PCB) is attached to the toplayer of the implant, with the PCB having first and second opposingsides. A neural interface attaches to the second side of the PCB. A coresubsystem (CSS) attaches to the first side of the PCB and electricallyconnects to the neural interface. An internal radio frequency (RF)interface attaches to the first side of the PCB and is electricallyconnected to the CSS. The power may be supplied by RF energy emittedfrom the external subsystem.

In some embodiments, the external subsystem includes a controller. Thecontroller may include a port for interfacing with a computer. Acomputer may interface with the controller through the port to programpatient-specific nerve physiology and stimulation parameters into thecontroller. The controller may be shaped for placement around apatient's ear. The controller may identify an implant having a unique IDtag, communicate with an implant having the unique ID tag, and send asignal to a transponder located in the implant. In some embodiments, thetransponder is a passive RFID transponder. In other embodiments, thetransponder is an active transponder. In still further embodiments, thecontroller provides an RF signal to the implant, senses and recordsdata, and interfaces with a programming device. The controller may alsocommunicate with the implant at preprogrammed intervals. In otherembodiments, the controller initiates a stimulation cycle by making arequest to the CSS, the request being in the form of an encoded RFwaveform including control data. The request may be encrypted.

In some embodiments, the implant provides continuous open loopelectrical stimulation to the HGN. In other embodiments, the implantprovides closed loop stimulation. The stimulation may be constant, or itmay be at preprogrammed conditions. Stimulation may be applied duringsleep hours, or it may be applied while the patient is awake. Thestimulation may be bi-phasic stimulation of the HGN, with a stimulationpulse width of about 200 microseconds and a stimulation frequency ofabout 10-40 Hertz. The implant may be hermetically sealed. In otherembodiments, the implant delivers multiple modes of stimulation. Thestimulation can be in multiple dimensions.

Stimulation may be provided by a neural interface. This stimulation maybe applied to the HGN. In certain embodiments, the neural interfaceincludes a plurality of individual electrodes. In further embodiments,the neural interface electrodes include an array of anodes and cathodes,which in some embodiments are a plurality of exposed electrode pairsserving as anode and cathode complementary elements. In certain otherembodiments, the electrodes are spot welded to the PCB and includematerial selected from the group consisting of platinum and iridium. Incertain embodiments, the neural interface includes no external wires orleads. In still further embodiments, the neural interface includes amatrix of platinum electrodes coupled to the fascicles of thehypoglossal nerve (HGN). In some embodiments, the neural interfacesenses neural activity of the nerve it interfaces with, and transmitsthat sensed neural activity to the core subsystem.

In some embodiments, the core subsystem (CSS) of the implant is includedin a silicon chip placed on the top of the printed circuit board PCB,with the chip connected to the neural interface via traced wires printedon the PCB. The chip may be powered by and receive a customizedelectrode stimulation program protocol from the controller. Uponreceiving a request to enter into a stimulation state the CSS selects atrained waveform from memory and starts stimulation by providing anelectrical signal to the neural interface. In some embodiments, the coresubsystem reports completion of a stimulation state to the controllervia an RF communication and optionally goes to an idle state.

Methods for treating obstructive sleep apnea are also disclosed. In onemethod, a hypoglossal nerve (HGN) is selectively stimulated. A neuralinterface is implanted in a fascicle of the HGN. The neural interfacesenses and records neural activity, and feeds the sensed neural activityinformation into a parameterized control algorithm. In certainembodiments, an external subsystem inductively coupled to an RFID sensesand records the neural activity. The algorithm compares the sensedinformation to a reference data set in real time, transmits in real timean output of the parameterized control algorithm from an external RFinterface to an internal RF interface, and from the internal RFinterface to a microprocessor. Stimulus information may be calculatedand communicated between the external RF interface and the internal RFinterface in real time. In another method, bi-phasic electricalstimulation is applied to individual fascicles of the hypoglossal nerveusing selectively excitable individual electrodes arranged in a planarfield.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 shows an embodiment of an internal subsystem.

FIG. 2 shows an embodiment of an internal subsystem with the coresubsystem and internal RF interface in a silicon package.

FIG. 3 shows a hypoglossal nerve an implant.

FIG. 4 shows multiple embodiments of neural interface electrode arrays.

FIG. 5 shows an embodiment of an internal subsystem implant.

FIG. 5A is a breakout view of FIG. 1.

FIG. 6A shows an embodiment of an internal subsystem with the neuralinterface electrodes on the bottom layer of the implant.

FIG. 6B shows an embodiment of an internal subsystem with the neuralinterface electrodes on the top and bottom layers of the implant.

FIG. 7 shows an embodiment of an external subsystem with a controller.

FIG. 8 shows two embodiments of the external controller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

One embodiment the present invention includes an external subsystem andan internal subsystem. In certain embodiments, the external subsystemincludes one or more of (1) a controller, (2) an external RF interface,and (3) an optional power source. The internal subsystem may include animplant. In certain embodiments, the implant includes one or more of (1)a neural interface which can include an array of electrodes where atleast one electrode contacts a nerve, (2) a core subsystem, and (3) aninternal RF interface. In some embodiments, the neural interface mayfurther include a digital to analog signal converter and a multiplexer.

In some embodiments the core subsystem may include a microprocessor. Themicroprocessor may have a micrologic CPU and memory to store protocolsselective to a patient. The microprocessor may be part of an integratedsilicon package. In still further embodiments, the internal RF interfacemay include one or more of a transponder, internal antenna, modulator,demodulator, clock, and rectifier. The transponder can be passive oractive. In some embodiments, one or more of a controller, external RFinterface, and optional power source are positioned on the skin of auser/patient, typically directly over or in close proximity to, animplant.

In certain embodiments, the external subsystem controller can be in theform of an earpiece or patch including any one or more of thecontroller, external RF interface, and optional power source, e.g., abattery, AC to DC converter, or other power sources known to thoseskilled in the art. In certain embodiments, the external subsystem cansend and receive control logic and power using an external RF interface.In such embodiments, the external subsystem can further include one ormore of a crypto block, data storage, memory, recording unit,microprocessor, and data port. In some embodiments the microprocessormay have a micrologic CPU and memory to store protocols selective to apatient. The microprocessor may be part of an integrated siliconpackage.

Each of the components of various embodiments of the claimed inventionis described hereafter. In certain embodiments, the present invention isan open loop system. In other embodiments the present invention is aclosed loop system. The components of the embodiments can be rearrangedor combined with other embodiments without departing from the scope ofthe present invention.

The Internal Subsystem

In certain embodiments, the internal subsystem includes an implant,which includes one or more of (1) a core subsystem, (2) a neuralinterface, and (3) an internal RF interface. Certain embodiments of theimplant components and component arrangements are described below.

Implant Components

The following paragraphs describe embodiments of the implant of thepresent invention, which includes one or more of a core subsystem,neural interface, and internal RF interface components.

The Core Subsystem

FIG. 1 shows an embodiment of the internal subsystem 100. In certainembodiments the internal subsystem 100 includes an implant 105(non-limiting representative embodiments of implant 105 are shown inFIGS. 3, 5, 5A, 6A, 6B, and 8) which may have a core subsystem 140. Themiddle portion of FIG. 1 shows a detailed view of an embodiment of thecore subsystem 140. The core subsystem 140 may include one or more of apower module 144, microprocessor 141, crypto block 142, and input outputbuffer 143. In certain embodiments, the microprocessor 141 may have amicrologic CPU, and may have memory to store protocols selective to apatient. In the embodiment shown, the core subsystem includes a powermodule 144, a core subsystem microprocessor 141 for managingcommunication with an external RF interface 203, at least one I/O buffer143 for storing inbound and outbound signal data, and a core subsystemcrypto block 142. In some embodiments, the core subsystem microprocessor141 communicates with the external RF interface 203 in full duplex. Thecore subsystem microprocessor 141 may generate signals for controllingstimulation delivered by the neural interface 160, and it may processessignals received from the neural interface 160. In certain embodiments,the core subsystem microprocessor logic includes an anti-collisionprotocol for managing in-range multiple transponders and readers, amanagement protocol for reset, initialization, and tuning of the implant105, and a protocol to facilitate the exchange of data with the neuralinterface 160. The core subsystem microprocessor 141 is programmable andmay further include an attached non-volatile memory. The microprocessor141 may be a single chip 145 or part of an integrated silicon package170.

FIG. 2 shows an embodiment of an internal subsystem 100 with the coresubsystem 140 and internal RF interface 150 in a silicon package 170.For size comparison, FIG. 2 shows the core subsystem 140, internal RFinterface 150, and core subsystem microprocessor 141 next to the siliconpackage 170.

The Neural Interface

The right portion of FIG. 1 shows an embodiment of a neural interface160. The neural interface 160 can include an array of electrodes 161where at least one electrode 161 contacts a nerve. In one embodiment,the neural interface 160 includes an array of 10 to 16 electrodes 161.This arrangement is exemplary only however, and not limited to thequantity or arrangement shown. The core subsystem 140 connects to theneural interface 160, and controls neural interface stimulation. In theembodiment shown, the neural interface 160 is attached to the printedcircuit board 130. In some embodiments, the neural interface 160 mayfurther include a digital to analog signal converter 164 and amultiplexer 166. In certain embodiments the multiplexer 166 is includedon the printed circuit board 130. In other embodiments, the multiplexer166 is included on a thin layer film or flexible membrane around thesurface of the chip.

In the embodiment shown, the neural interface 160 receives power from RFwaves received by the implant 105. In one embodiment, the D/A converter164 uses the RF waves to power one or more capacitors 165, which may belocated in the converter 164. In certain embodiments, the capacitors 165are arranged in an array on a microfilm. These capacitors 165 storecharges, which are used to generate analog burst pulses for delivery bythe neural interface 160. In embodiments including a multiplexer 166,the multiplexer 166 may be used to deliver power to multiple capacitors165, and can be used to deliver power to multiple electrodes 161 in theneural interface 160. In still further embodiments, the multiplexer 166is programmable.

In certain embodiments, the neural interface 160 is physically locatedon the opposite side of the printed circuit board 130 to which the coresubsystem 140 is attached. In other embodiments, the one or moreelectrodes 161 are physically separated from the core subsystem 140 bythe printed circuit board 130. Each electrode 161 connects to the coresubsystem 140 through wires 133 (e.g., traced wires) on the printedcircuit board 130. This layered approach to separating the coresubsystem 140 from the electrodes 161 has significant benefits in thebio-compatible coating and manufacturing of the implant. By minimizingthe area exposed to the HGN, the bio-compatible coating is only requiredin the area surrounding the exposed parts of the electrodes 161.

The electrodes 161 may be manufactured with biocompatible materialcoating. In certain embodiments, the electrodes may include embeddedplatinum contacts spot-welded to a printed circuit board 130 on theimplant 105. The electrodes 161 may be arrayed in a matrix, with thebottoms of the electrodes 161 exposed for contact to the HGN. Since theelectrodes 161 attach to the top portion of the core subsystem 140through leads on the printed circuit board, there is no need forwire-based leads attached to the contact points, allowing forminiaturization of the electrodes 161.

FIG. 3 shows a hypoglossal nerve implanted with a neural interface 160.In one embodiment, exposed portions of the neural interface 160 deliverselective stimulation to fascicles of the HGN. Selective stimulationallows co-activation of both the lateral HGN branches, which innervatethe hypoglossus (HG) and styloglossus (SG), and the medial branch. Thisselective stimulation of HG (tongue retraction and depression) and theSG (retraction and elevation of lateral aspect of tongue) results in anincreased maximum rate of airflow and mechanical stability of the upperairway (UAW). Selective stimulation is a unique approach to nervestimulation when implanted on the hypoglossal nerve (HGN). The neuralinterface 160 may also sense the neural activity of the nerve itinterfaces with and may transmit that sensed activity to the coresubsystem microprocessor 141.

FIG. 4 shows embodiments of neural interface electrode arrays. Theseembodiments are exemplary only, and the arrays are not limited to thequantity or arrangement of the electrodes shown in the figure. In oneembodiment, at least one electrode 161 is in contact with a nerve. Incertain embodiments, the electrodes 161 may be in the shape of a linear,regular, or irregular array. In certain embodiments, the electrode 161array may be in a form suitable for wrapping around a nerve (e.g., ahelical shape or spring-like shape as shown in FIG. 3). The electrodes161 may also be arranged in a planar form to help reshape the nerve andmove the axons closer to the electrodes 161. This facilitates access tomultiple nerve axons, which enables multiple modes of stimulation forenhanced UAW dilation and stability. With a planar form factor,stimulation can also be delivered in two dimensions, enabling optimalexcitation of the functional branches of the nerve. Excitation happensthrough bi-phasic electrical stimulation of individual electrodes 161.

The Internal RF Interface

The left portion of FIG. 1 shows a detailed view of an embodiment of theinternal RF interface 150. The internal RF interface 150 may include oneor more of a transponder 156, internal antenna 151, modulator 157,demodulator 158, clock 159, and rectifier. The transponder 156 can bepassive or active. In certain embodiments, the internal RF interface 150can send and/or receive one or more of (1) control logic, and (2) power.In still further embodiments, the internal RF interface 150 delivers oneor more of power, clock, and data to the implant core subsystem 140. Incertain embodiments the data is delivered via a full duplex dataconnection. In some embodiments, the internal RF interface 150 sendsdata (e.g., function status) of one or more electrodes 161 to acontroller 205, described below, for review by a technician orphysician.

The internal RF interface 150 operates according to the principle ofinductive coupling. In an embodiment, the present invention exploits thenear-field characteristics of short wave carrier frequencies ofapproximately 13.56 MHz. This carrier frequency is further divided intoat least one sub-carrier frequency. In certain embodiments, the presentinvention can use between 10 and 15 MHz. The internal RF interface 150uses a sub carrier for communication with an external RF interface 203,which may be located in the controller 205. The sub-carrier frequency isobtained by the binary division of the external RF interface 203 carrierfrequency. In the embodiment shown, the internal RF interface 150 isrealized as part of a single silicon package 170. The package 170 mayfurther include a chip 145 which is a programmable receive/transmit RFchip.

In certain embodiments, the internal RF interface 150 also includes apassive RFID transponder 156 with a demodulator 158 and a modulator 157.The transponder 156 uses the sub carrier to modulate a signal back tothe external RF interface 203. In certain embodiments, the transponder156 may further have two channels, Channel A and Channel B. Channel A isfor power delivery and Channel B is for data and control. Thetransponder 156 may employ a secure full-duplex data protocol.

The internal RF interface 150 further includes an inductive coupler 152,an RF to DC converter 155, and an internal antenna 151. In certainembodiments, the internal antenna 151 includes a magnetic component. Insuch embodiments, silicon traces may be used as magnetic antennas. Inother embodiments, the antenna may be a high Q coil electroplated onto asilicon substrate. A parallel resonant circuit 153 may be attached tothe internal antenna 151 to improve the efficiency of the inductivecoupling. The internal antenna 151 may be realized as a set of PCBtraces 133 on the implant 105. Size of the antenna traces is chosen onthe basis of power requirements, operating frequency, and distance tothe controller 205. Both the internal RF interface 150 and the coresubsystem microprocessor 141 are powered from an RF signal received bythe internal antenna 151. A shunt regulator 154 in the resonant circuit153 keeps the derived voltage at a proper level.

Implant Component Arrangement

The implant 105 may be located on any suitable substrate and may be asingle layer or multi-layer form. FIG. 5 shows an implant 105constructed as a single integrated unit, with a top layer 110 and abottom layer 110 which may be implanted in proximity to, in contactwith, or circumferentially around a nerve, e.g., the hypoglossal nerve.FIG. 5A is a breakout view of FIG. 5.

In certain embodiments, implant components are layered on a nerve. Thisalleviates the need for complex wiring and leads. In FIGS. 5 and 5A, thetop layer 110 includes a core subsystem 140, an internal RF interface150, and a neural interface 160. The top layer 110 serves as theattachment mechanism, with the implant components on the bottom layer110. The neural interface 160 may be surface bonded to contacts on aprinted circuit board 130. The bottom layer 110 is complementary to thetop layer 110, and serves as an attachment mechanism so that the implant105 encompasses the HGN. Although conductive parts in contact with theHGN may be located at any suitable position on the implant 105, in theembodiment shown in FIGS. 5 and 5A, the bottom layer 110 has noconductive parts.

In the embodiment shown in FIGS. 5 and 5A, and as described above, thecore subsystem 140 is included in a silicon package 170 (FIG. 2)attached to a printed circuit board (PCB) 130 on the top layer 110. ThePCB 130 has a first side 131 and a second side 132. The silicon package170 is placed on a first side 131 of the printed circuit board 130. Incertain embodiments the PCB 130 may be replaced with a flexible membranesubstrate. In the embodiment shown, the silicon package 170 furtherincludes the internal RF interface 150. The neural interface 160attaches to the second side 132 of the PCB 130. In this embodiment, theneural interface 160 (FIG. 6B) further includes a plurality of neuralinterface electrodes 161 (FIG. 4) arranged into anode and cathode pairs162/163, shown in this embodiment as an array of 10 to 16 elements. Thenumber and arrangement of anode and cathode pairs 162/163 is exemplaryonly, and not limited to the embodiment shown. The silicon package 170(FIG. 2) connects to the anode and cathode pairs 162/163 via tracedwires 133 printed on the PCB 130.

In other embodiments, such as the one shown in FIG. 6A, the neuralinterface electrode anode and cathode pairs 162/163 are located on thebottom layer 110 of the implant 105. In still other embodiments, such asthe one shown in FIG. 6B, the neural interface electrode anode andcathode pairs 162/163 are located on both the top and the bottom layers110/120. The matrix arrangement of electrodes 161 provides multiplenerve stimulating points, and has several advantages. The matrixarrangement allows a web of nerve fascicles of the hypoglossal nerve tobe accessed, enabling selective stimulation of particular areas of thenerve. In some embodiments, power is delivered to the matrix ofelectrodes 161 from the D/A converter 164 to capacitors 165 via amultiplexer 166.

The implant 105 may further include an isolation layer 112 (FIG. 6A). Incertain embodiments a protective coating 114 (FIGS. 6A and 6B) may beapplied to the top and bottom layers 110/120 of the implant 105. Theimplant 105 may further be coated with a protective coating 114 forbiological implantation. Further, in certain embodiments all or aportion of the device may be encased in a biocompatible casing. In suchembodiments, the casing may be a material selected from the groupconsisting of one or more titanium alloys, ceramic, andpolyetheretherketone (PEEK).

The External Subsystem

In certain embodiments, the external subsystem 200 may include one ormore of (1) a controller, (2) an external RF interface and (3) anoptional power source. An embodiment of an external subsystem 200including these elements is shown in FIG. 7. Typically the externalsubsystem 200 is located externally on or near the skin of a patient.

The Controller

FIG. 7 shows an embodiment of an external subsystem 200 with acontroller 205. The controller 205 controls and initiates implantfunctions. In other embodiments, the controller 205 may be part of theinternal subsystem 100 instead of external subsystem 200, and in stillfurther embodiments, portions of the controller 205 may be in both theexternal and internal subsystems 200/100. In certain embodiments, thecontroller 205 may further have one or more of a controller crypto block201, data storage 206, a recording unit 207, and a controllermicroprocessor 204. In some embodiments the controller microprocessor204 may have a micrologic CPU and memory to store protocols selective toa patient. The controller microprocessor 204 is programmable and mayfurther include an attached non-volatile memory. The microprocessor 204may be a single chip or part of an integrated silicon package.

In certain embodiments, the controller may further include includes oneor more of an external RF interface having RF transmit and receivelogic, a data storage that may be used to store patient protocols, aninterface (e.g., a USB port), a microprocessor, an external antenna, afunctionality to permit the controller to interface with a particularimplant, and an optional power source. In certain embodiments, thecontroller electronics can be either physically or electromagneticallycoupled to an antenna. The distance between the external RF interfaceantenna (not shown) and the implant 105 may vary with indication. Incertain embodiments, distance is minimized to reduce the possibility ofinterference from other RF waves or frequencies. Minimizing the distancebetween the external antenna and the implant 105 provides a better RFcoupling between the external and internal subsystems 200/100, furtherreducing the possibility of implant activation by a foreign RF source.An encrypted link between the external and internal subsystems 200/100further reduces the possibility of implant activation by foreign RF. Inother embodiments, one or more of the internal antenna 151 and externalantennas 209 are maintained in a fixed position. Potential designcomplexity associated with internal RF interface antenna 151 orientationis minimized through the ability to position the external RF interfaceantenna in a specific location (e.g., near the patient's ear). Even ifthe patient moves, the internal RF interface antenna 151 and controller205 remain coupled.

In certain other embodiments, the controller 205 can also serve as (1) adata gathering and/or (2) programming interface to the implant 105. Thecontroller 205 has full control over the operation of the implant 105.It can turn the implant 105 on/off, and may be paired to the implant 105via a device specific ID, as described herein below with respect to useof the implant 105 and controller 205 of the present invention. In stillfurther embodiments, the controller microprocessor 204 calculatesstimulus information. The stimulus information is then communicated tothe implant 105. The implant 105 then provides a calculated stimulus toa nerve. In another embodiment, the controller 205 preloads the implant105 with an algorithmic protocol for neural stimulation and thenprovides power to the implant 105.

External RF Interface

In the embodiment shown in FIG. 7, the external subsystem 200 includesan external RF interface 203 that provides an RF signal for powering andcontrolling the implant 105. The external RF interface 203 can berealized as a single chip, a plurality of chips, a printed circuitboard, or even a plurality of printed circuit boards. In otherembodiments, the printed circuit board can be replaced with a flexiblemembrane. The external RF interface 203 may include one or more of atransponder 208 (not shown), external antenna (not shown), modulator 210(not shown), and demodulator 211 (not shown), clock 212 (not shown), andrectifier 213 (not shown) (not shown). The external RF interfacetransponder 208 can be passive or active. In certain embodiments, theexternal RF interface 203 can send and/or receive one or more of (1)control logic, and (2) power. In still further embodiments, the externalRF interface 203 delivers one or more of power, clock, and data to oneor more of the external subsystem controller 205 and the internalsubsystem 100 via the internal RF interface 150. In certain embodimentsthe data is delivered via a full duplex data connection. In anembodiment, the external RF interface 203 operates at a carrierfrequency of approximately 13.56 MHz. In certain embodiments, theexternal RF interface 203 can operate between 10 and 15 MHz. Thiscarrier frequency is further divided into at least one sub-carrierfrequency. The sub-carrier frequency is obtained by binary division ofthe external RF interface 203 carrier frequency. The external RFinterface 203 uses the sub carrier for communication with the internalRF interface 150. The external RF interface transponder 208 (not shown)uses the sub carrier to modulate a signal to the internal RF interface150. The transponder 208 (not shown) may further have two channels,Channel A and Channel B. Channel A is for power delivery and Channel Bis for data and control. The transponder 208 (not shown) may employ asecure full-duplex data protocol.

In certain embodiments, the external RF interface 203 may furtherinclude a demodulator 211 (not shown) and a modulator 210 (not shown).In still further embodiments, the external RF interface 203 furtherincludes an external antenna. In certain embodiments, the externalantenna includes a magnetic component. In such embodiments, silicontraces may be used as magnetic antennas. The antenna may be realized asa set of PCB traces. Size of the antenna traces is chosen on the basisof power requirements, operating frequency, and distance to the internalsubsystem 100. In certain embodiments, the external antenna may transmitthe power received by internal subsystem 100. In certain otherembodiments, the external antenna may be larger, and have a higher powerhandling capacity than the internal antenna 151, and can be realizedusing other antenna embodiments known by those skilled in the art.

In certain embodiments, the external subsystem 200 is loosely coupled toan optional power source 215. In one embodiment, the controller powersource 215 is not co-located with the external RF interface antenna. Theexternal power source 215 may be in one location, and the external RFinterface 203 and optionally the controller 205 are in a second locationand/or third location. For example, each of the power source 215,controller 205 and external RF interface 203 can be located indifference areas. In one embodiment, the power source 215 and thecontroller 205 and the external RF interface 203 are each connected byone or more conductive members, e.g. a flexible cable or wire.Additionally, in certain embodiments, the controller 205 and optionalpower source 215 may be co-located, and the external RF interface 203may be located elsewhere (i.e., loosely coupled to the controller 205).In such embodiments, the external RF interface 203 is connected to thecontroller 205 by a flexible cable or wire.

Since the power source 215 may be separately located from the controller205 and/or external RF interface antenna, a larger power source 215 canbe externally located but positioned away from the nerve that requiresstimulation. Further, to reduce wasted power, a larger external RFinterface antenna can be used. This provides the advantage of lessdiscomfort to a user and therefore enhances patient compliance.

Such embodiments can also provide power to 2, 3, 4, 5 or more looselycoupled external RF interfaces 203. Thus, each external RF interface 203can be positioned at or near the site of an implant 105 without the needfor a co-located power source 215. In certain embodiments, each externalRF interface 203 draws power from a single power source 215, and thus asingle power source 215 powers a plurality of implants 105. Of course,the amount of power provided to each implant 105 will vary by indicationand distance between the external RF interface 203 and the implant 105.The greater the distance between the external RF interface 203 and theimplant 105, the greater the power level required. For example, a lowerpower is generally required to stimulate peripheral nerves, which arecloser to the surface of the skin. As apparent to one of skill in theart, the power received at the implant 105 must be high enough toproduce the desired nerve stimulus, but low enough to avoid damaging thenerve or surrounding tissue.

The external RF interface 203 may further include a programmablereceive/transmit RF chip, and may interface with the controller cryptounit 201 for secure and one-to-one communication with its associatedimplant 105. The external RF interface 203 includes a parameterizedcontrol algorithm, wherein the parameterized control algorithm comparesthe sensed information to a reference data set in real time. Thealgorithm may be included in the controller microprocessor 204.Depending upon the patient's size and severity of disease state, thealgorithm will vary a number of parameters which include frequency,amplitude of the signal, number of electrodes involved, etc.

Interaction with Outside Information Sources

The external subsystem controller 205 may also interface with acomputer. In some embodiments, the controller interface 202 is abuilt-in data port (e.g., a USB port). Via the controller interface 202a computer may tune (and re-tune) the implant system, and transferhistorical data recorded by the implant 105. The controller 205 mayobtain and update its software from the computer, and may upload anddownload neural interface data to and from the computer. The softwaremay be included in the controller microprocessor 204 and associatedmemory. The software allows a user to interface with the controller 205,and stores the patient's protocol program.

External Subsystem Design

The external subsystem 200 can be of regular or irregular shape. FIG. 8shows two embodiments of an external subsystem controller 205, one withthe controller 205 included with an earpiece much like a Bluetoothearpiece, and one with the controller 205 included with a patch. In theembodiments shown, potential design complexity associated with internalRF antenna 151 orientation is minimized through the single and fixedposition of the controller 205. The patient may move and turn withoutdisrupting the coupling between the controller 205 and the internalantenna 151. In the embodiment with the controller 205 in an earpiece, aflexible receive/transmit tip in the earpiece aligns the controllerexternal RF interface antenna with the implant 105. In the embodimentwith the controller 205 in a patch, the patch is aligned with theimplant 105 and placed skin. The patch may include one or more of thecontroller 205, a replaceable adhesive layer, power and RFID couplingindication LED, and a thin layer rechargeable battery. Still furtherembodiments include incorporation of the external subsystem 200 into awatch-like device for, e.g., the treatment of arthritic pain, or in abelt. Yet another range of variations are flexible antennas and thecontroller RF chip woven into clothing or an elastic cuff, attached tocontroller electronics and remotely powered. Controller 205 designs maybe indication specific, and can vary widely. The controller 205embodiments in FIG. 8 are exemplary only, and not limited to thoseshown.

Communication with the Implant as a Function of Design

The distance between this contact area and the actual implant 100 on anerve is 1 to 10 cm, typically 3 cm, through human flesh. This distance,along with the controller crypto unit 201 and the core subsystem cryptounit 142 in the implant 100, reduces potential interference from otherRF signals.

Implant and Controller Positioning

Prior to implantation of the present invention for the treatment ofsleep apnea, patients are diagnosed in a sleep lab, and an implant 105is prescribed for their specifically diagnosed condition. Once diagnosisis complete, the implant 105 is surgically implanted in the patient'sbody, typically on or in the vicinity of a nerve. In certainembodiments, the implant 105 is implanted on the HGN. In suchembodiments, the implant 105 may be implanted below the ear unilaterallyat the sub-mandibular triangle, encasing the hypoglossal nerve.

Stimulation of the HGN can act to maintain nerve activity. Hence incertain embodiments, the present invention can maintain muscular tone(e.g., in the tongue, thereby preventing apnea). Therefore, in certainembodiments, controller 205, described in more detail above, activatesimplant 105 to stimulate HGN activity to ameliorate the negativephysiological impact associated with insufficient tone muscles causedby, e.g., insufficient HGN activity.

Once implanted, the implant 105 is used to stimulate the nerve. Inembodiments where the device is implanted in a manner to stimulate theHGN, the implant 105 delivers tone to the tongue. Maintaining tonguemuscle tone stops the tongue from falling back and obstructing the upperairway. The stimulation may be provided continuously during sleep hours,or upon preprogrammed patient-specific intervals. The implant 105 mayalso sense and record neural activity.

Implant and Controller Security

In certain embodiments, the controller 205 identifies the patient'sunique ID tag, communicates with and sends signals to the implant 105.In certain embodiments, a controller crypto unit 201 may be installed toensure that communication between the controller 205 and the implant 105is secure and one-to-one. The controller crypto unit 201 may include theimplant's unique ID tag.

In particular, the implant 105 may have a unique ID tag, which thecontroller 205 can be programmed to recognize. A controllermicroprocessor 204 confirms the identity of the implant 105 associatedwith the controller 205, thereby allowing setting of the patient'sspecific protocol. The setting may be accomplished using a computerinterfaced with the controller 205 through an interface 202 on thecontroller 205.

More particularly, once the controller crypto unit 201 establishes alink with the core subsystem crypto unit 142, the controller 205communicates a stimulation scenario to the core subsystem microprocessor141. The controller 205 initiates a stimulation cycle by making arequest to the core subsystem 140 by sending an encoded RF waveformincluding control data via the external RF interface 203. The coresubsystem 140 selects a trained waveform from memory and transmits thestimulation waveform to the core subsystem microprocessor 141. Once thecore subsystem microprocessor 141 receives the waveform, the coresubsystem 140 generates a stimulating signal for distribution to theneural interface 160.

Interaction with the Implant

In certain embodiments, the controller 205 prevents self-activation orautonomous operation by the implant 105 by handshaking. Handshakingoccurs during each communications cycle and ensures that security ismaintained. This prevents other devices operating in the same frequencyrange from compromising operation of the implant 105. Implant stimuluswill not commence unless an encrypted connection is established betweenthe external RF interface 203 and the implant 105. This serves as ananti-tampering mechanism by providing the implant 105 with a unique IDtag. The external controller 205 is matched, either at the pointmanufacture or by a physician, to a particular ID tag of the implant105, typically located in an EPROM of the implant 105. In certainembodiments, the EPROM may be included in the core subsystemmicroprocessor 141. In other embodiments, the EPROM may be included inthe controller microprocessor 204. This prevents alien RF interferencefrom ‘triggering’ activation of the implant 105. While arbitrary RFsources may provide power to the implant 105, the uniquely matchedcontroller 205 establishes an encrypted connection before directing theimplant 105 to commence stimulus, thereby serving as a securitymechanism.

System Programming

Desired system programming is determined by measuring a patient's tongueactivity against predetermined stimulation protocols. The effectivenessof the neural interface 160 stimulation protocols are measured until adesired tongue stimulation level is achieved. Once a desired tonguestimulation level is achieved, those protocols are programmed into thecontroller 205. Stimulation may be programmed for delivery in an openloop or closed loop at a suitable frequency. In certain embodiments, astimulation frequency of about 10-40 Hz is used. Stimulation may also bedelivered in pulses, with pulse widths about 100 to 300 microseconds,more typically 200 microseconds. Although any suitable pulse width canbe used, preferred pulses are at a width that simultaneously preventnerve damage and reduce or eliminate corrosion of neural interfaceelectrodes. After the controller 205 is programmed, the patientactivates the controller 205 at bed time or at desired intervals.

In certain embodiments, controller 205 can also determine when thepatient is asleep, and stimulate the HGN based on that determination. Inorder to determine when the patient is asleep, controller 205 caninclude one or more sensors that generate signals as a function of theactivity and/or posture of the patient. In such embodiments, controller205 determines when the patient is asleep based on the signal.Controller 205 can also have an acoustic sensor, to indicate whensnoring starts, and can determine whether the patient is asleep based onthe presence of snoring. In other embodiments the patient may enter aninput into the controller 205 telling it to commence treatment. However,as noted above, controller 205 can be activated by a user and thenfunction in a manner such that the implant is continuously active untilthe patient awakens and manually deactivates the controller by pressinga button on the controller 205 or by moving the controller 205 out ofrange of the implant.

This electrical stimulation provides a signal to the HGN and starts thetreatment of the airway obstruction. Upon completion of one cycle, theduration of which is determined in the tuning phase of the implantationprocedure, described above, the core subsystem 140 can report completionback to the controller 205 via RF communication, and optionally goes toan idle state until receiving another set of instructions.

As described above, in certain embodiments, the implant 105 isexternally powered by near field RF waves, the RF waves are inductivelyconverted to DC power, which powers the implant 105 and deliverselectrical signals to selected elements of the neural interface 160. Theimplant uses between 0.1 to about 1 milliamps, preferably averagingabout 0.5 milliamps of current and about 10 to 30 microwatts of power.

In some embodiments, the near field RF waves are emitted from thecontroller 205. In certain embodiments, controller 205 can be powered byan optional power source 215, e.g., a battery, AC to DC converter, orother power source known to those skilled in the art.

Other embodiments of the apparatus and methods described can be used inthe present invention. Various alternatives, substitutions andmodifications for each of the embodiments and methods of the inventionmay be made without departing from the scope thereof, which is definedby the following claims. All references, patents and patent applicationscited in this application are herein incorporated by reference in theirentirety.

1-44. (canceled)
 45. An implantable neurostimulator for treatingobstructive sleep apnea in a patient comprising: an implantable nervecuff configured to at least partially wrap around a segment of aHypoglossal nerve (HGN), the nerve cuff including a plurality ofelectrodes each oriented and configured to contact the HGN at differentradial locations of the segment of the HGN; an implantable coresubsystem electrically coupled to the nerve cuff; and an externalcontroller in communication with the implantable core subsystem andconfigured to control electrical stimulation applied to the HGN throughthe plurality of electrodes.
 46. The implantable neurostimulator ofclaim 45, wherein the core subsystem includes a printed circuit board(PCB).
 47. The implantable neurostimulator of claim 46, wherein the coresubsystem includes a radio frequency (RF) interface electrically coupledto the PCB and in RF communication with the controller.
 48. Theimplantable neurostimulator of claim 45, wherein the controller isconfigured to initiate a stimulation cycle of the HGN.
 49. Theimplantable neurostimulator of claim 48, wherein the initiation of thestimulation cycle is conditional on one or more of activity and postureof the patient determined by a sensor in communication with thecontroller.
 50. The implantable neurostimulator of claim 45, wherein thecore subsystem is configured to report completion of a stimulation stateto the controller and then go to an idle state.
 51. The implantableneurostimulator of claim 45, wherein at least two of the plurality ofelectrodes are arranged at different longitudinal positions with respectto the HGN when the nerve cuff is wrapped around the HGN.
 52. Theimplantable neurostimulator of claim 45, wherein the nerve cuff isconfigured to completely radially wrap around the segment of the HGN.53. The implantable neurostimulator of claim 45, wherein the pluralityof electrodes are configured to provide continuous open loop electricalstimulation to the HGN during sleep hours.
 54. The implantableneurostimulator of claim 45, wherein the nerve cuff is configured todeliver multiple modes of stimulation.
 55. The implantableneurostimulator of claim 45, wherein the plurality of electrodes areconfigured to provide bi-phasic stimulation of the HGN.
 56. Theimplantable neurostimulator of claim 45, wherein the controller isconfigured to stimulate patient specific nerve physiology andstimulation parameters.
 57. The implantable neurostimulator of claim 45,wherein the plurality of electrodes are programmable to maximize rate ofairflow and stability of the upper airway.
 58. The implantableneurostimulator of claim 45, wherein the plurality of electrodes areconfigured to provide stimulation to different fascicles of HGN atpreprogrammed conditions.
 59. The implantable neurostimulator of claim45, wherein each of the plurality of electrodes is oriented andconfigured to contact a different web of nerve fascicles of the HGN. 60.The implantable neurostimulator of claim 45, wherein the plurality ofelectrodes are configured and arranged to enable selective stimulationof both lateral HGN branches.
 61. The implantable neurostimulator ofclaim 45 further comprising: a multiplexer electrically coupled to theplurality of electrodes, the multiplexer being programmable andconfigured to enable selective stimulation of particular areas of theHGN.
 62. An implantable neurostimulator system for treating obstructivesleep apnea, comprising: an implant configured to at least partiallysurround a portion of a Hypoglossal nerve (HGN); a printed circuit board(PCB) electrically coupled to the implant; a neural interfaceelectrically coupled to the PCB; a core subsystem (CSS) electricallycoupled to the PCB and electrically connected to the neural interface,the core subsystem being configured to select a trained waveform frommemory and start stimulation by providing an electrical signal to theneural interface upon receiving a request to enter into a stimulationstate, the core subsystem being configured to report completion of astimulation state to the controller via an RF communication and go to anidle state; a radio frequency (RF) interface electrically coupled to thePCB and electrically coupled to the CSS; and an external programmablecontroller configured to power and control the implant.
 63. Animplantable neurostimulator system for treating obstructive sleep apnea,comprising: an implant configured to and at least partially surround aportion of the Hypoglossal nerve (HGN); a printed circuit board (PCB)electrically coupled to the implant; a neural interface electricallycoupled to the PCB; a core subsystem (CSS) electrically coupled to thePCB and electrically coupled to the neural interface, the core subsystembeing included in a silicon chip placed on the PCB with the chipconnected to the neural interface via traced wires printed on the PCB; aradio frequency (RF) interface attached to the first side of the PCB andelectrically coupled to the CSS; and an external programmable controllerconfigured to power and control the implant.